1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a semiconductor device, and more particularly to a semiconductor device having a plurality of leads that are soldered on a printed circuit board (PCB).
2. Description of the Related Art
A field effect transistor (FET) that is a kind of semiconductor device is classified into a junction FET, a metal-oxide-semiconductor FET (MOS-FET), and a Gallium arsenide FET (GaAs FET). The junction FET is used in an analog circuit, such as an audio device, the MOS-FET is used in a digital integrated circuit (IC), such as a microcomputer, and the GaAs FET is used to amplify microwaves that are received through satellite broadcasting.
The FET is also classified into a small-signal transistor and a power transistor, and the power transistor typically has a power rating of more than 1 W. The maximum collector current and the maximum collector loss of the power transistor are greater than those of the small-signal transistor. The power transistor has a large size to cope with heat generation, and may be shielded by metal or may be provided with a heat dissipation fin.
However, in the case of the power transistor (e.g., FET for switching), leads are arranged with very narrow gaps between them. Accordingly, short circuits between adjacent leads may occur due to moisture condensation under high-moisture conditions, and a short circuit due to soldering ball inferiority between terminals and foreign substances may occur.
Further, in order to cool the heat generated from the power transistor, a frame portion is screw-engaged with a heat sink, and heat transfer compounds are spread on the frame portion and the heat sink to efficiently dissipate the heat generated from a semiconductor chip arranged inside the power transistor.
In this case, since a gap between the leads and the heat sink also becomes narrow, short circuits may occur between the respective leads.
In order to solve the problem of the short circuits that may occur due to the narrow gaps between the respective leads or between the leads and the heat sink, the semiconductor device is first soldered on the PCB, and then a predetermined amount of waterproofing material (e.g., sealant) is spread on the plurality of leads to insulate the plurality of leads and to remove inferiority elements, such as the short circuits between the leads.
However, since errors frequently occur in the spread positions of the waterproofing material during the waterproofing process, the short-circuit problem still remains unsolved, and the productivity is deteriorated due to additional waterproofing process to the manufacturing process.